Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
FXUS64 KHGX 281526
Area Forecast Discussion
National Weather Service Houston/Galveston TX
1026 AM CDT THU JUL 28 2016
Scattered showers and thunderstorms continue across the coastal
waters this morning, with additional development beginning to
occur along the coast as temperatures have risen into the mid 80s.
Main adjustments to the forecast this morning include raising PoPs
across the coastal waters and along the coast based on radar
trends as well as increasing PoPs for inland areas this afternoon.
Additional heating will promote scattered shower and thunderstorm
development (with best chances this afternoon north of Highway 59) as
temperatures rise into the low to mid 90s.
Morning soundings from Corpus Christi, Lake Charles, and
Shreveport reported precipitable water values remaining in the
1.9-2.2 range. The KHGX VAD wind profiler is showing 10-20 knot
southwest to south winds through about 15kft AGL (with
weak/variable mid level flow) and while this is not entirely
unidirectional flow, it is uniform enough to encourage some
training of slow-moving storms. This combined with ample moisture
means at least one more day of the potential for brief heavy
rainfall (isolated 1-3 inch amounts), possibly leading to minor
flooding concerns if cells repeatedly move across the same area.
Stronger cells will also be capable of gusty winds (25-35 MPH),
with all convection expected to dissipate by early evening with
loss of heating.
.PREV DISCUSSION... /ISSUED /
12Z TAF discussion...main concern will be the development of
convection later this morning and into the early afternoon. Radar
already shows some widely scattered activity in the gulf but not
much inland. Based on model soundings showing precip water values
around 2 inches, will need to warm into the upper 80s for
convective temp. Look for more showers to develop 15-17z inland
and along the coast. May get TSRA by 17-19z but do not think
coverage will be quite as much as the last few days. CIGS should
be VFR with some fog at KCXO giving the only MVFR CIG. Expect
convection to be ending 21-23z this afternoon with VFR overnight.
PREV DISCUSSION... /ISSUED /
The upper low that moved into the far eastern portion of the
state yesterday was sheared out this morning and well northeast of
the state. A look at the upper level systems affecting the pattern
over Southeast Texas showed two areas of high pressure, one over
the UT/AZ/NV border and another off the mid Atlantic coast. A
weakness in the ridge was located over our area with the eastern
high pressure area ridging across southeastern Louisiana into the
Upper Texas coastal areas. An upper low was moving slowly westward
across the north-central Gulf.
Moisture associated with the shearing out system will be generally
north and west of the forecast area today. A slightly drier
airmass associated with the upper level ridge will help lower the
rain chances today. However, enough will be present for isolated
to scattered coverage. Temperatures continue to be a challenge but
with less storm coverage, enough sun should appear for highs to
reach into the lower to mid 90s.
The models have divergent solutions on the evolution of the upper
level low over the north central Gulf during the next 24 to 48
hours. These include shearing out the system as it moves into
the Louisiana coast or shearing out the system as it moves into
the Upper Texas coast. If the second scenario pans out, slight
better chances of rain will be possible on Friday and maybe again
on Saturday. Otherwise, the models continue to fill in the upper
level weakness over the area. This will lead to mainly daytime
chances for showers and thunderstorms as the seabreeze becomes the
more dominate driver for convection. Daytime highs should reach
into the mid 90s with less cloud cover and slightly higher heights
Winds along the Upper Texas Coast are about 15 knots with seas
around 3-4ft or borderline SCEC conditions. Winds should decrease
during the day back to around 10 to 15 knots with seas closer to 3
feet. Radar shows some shower activity along the coast which
should move inland later this morning. Most thunderstorm activity
will be limited to inland areas during the day today. Light to
moderate winds are expected to continue through the weekend and
early next week. Seas should be limited to less than 3 feet for
the weekend. Tide levels will likely remain near normal levels or
maybe a half foot above normal.
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 94 76 96 77 96 / 30 10 20 10 10
Houston (IAH) 95 78 97 79 96 / 40 10 30 10 30
Galveston (GLS) 90 82 90 82 90 / 30 20 20 10 20